Ventilation perfusion functional difference images in lung SPECT: A linear and symmetrical scale as an alternative to the ventilation perfusion ratio

The current EANM guidelines emphasize the added diagnostic value of the ventilation-perfusion ratio (V/Q ratio, also coined the V/P quotient) on VQ scintigraphy, which is obtained by measuring the quantities V and Q in every voxel [1]. Ventilation (V) refers to the flow of air into and out of the airways and alveoli, while perfusion (Q) refers to the blood flow through the pulmonary circulation. On this basis, matched ventilation-perfusion defects (V/Q ratio ≈1) may easily be distinguished from ‘classical’ mismatched perfusion defects [2], that is, areas with reduced perfusion and maintained ventilation (high V/Q ratio), of which the former indicates ventilatory disturbance as can be seen in Covid-19 lung disease [3–5] and chronic obstructive pu lmonary disease (COPD) [6], whereas the latter is observed in pulmonary vascular disease, most notably pulmonary thromboembolism [7].
Source: Physica Medica: European Journal of Medical Physics - Category: General Medicine Authors: Source Type: research